The control of mold, mildew, algae, fungi, and other microbes or microorganisms in moist or humid environments has long been a matter of concern. Biocides such as mildewcide, anti-microbial, antiseptic, disinfectant, sanitizer, germicide, algaecide, slimicide, antifouling agent, or preservative are typically employed to remove microbes from an area and prevent their recurrence.
Absorbent articles used for cleaning (e.g., sponges and wiping articles) can harbor microorganisms such as bacteria and fungi that thrive and rapidly multiply in moist environments. In the food service and medical industries, sanitation and prevention of the spread of infections is of the utmost importance. Consequently, it is desirable to use materials which will control or prevent the growth of unwanted microorganisms. Various approaches have been taken to the problem of microbial growth in articles such as sponges and other wiping and cleaning articles, for example. Cellulose sponges treated with germicides and biocides, including alkali metal salts in combination with quaternary ammonium compounds as well as alkali metal montmorillonite clays, have been used with some success. Metal dialkyl dithiocarbamates have also been used as biocides in pigmented sponges. The sponges prepared by these methods, although initially effective, generally do not have long-lasting antimicrobial activity because the biocides tend to wash out of sponges upon rinsing with water or when the article is used in cleaning applications.
One approach to introducing a long-lasting anti-microbial agent into an absorbent sponge is described in U.S. Pat. No. 5,541,233 (Roenigk). Durable, long-lasting anti-microbial sponges are formed by mixing a metal ion and a dispersion of a chelating polymer with the viscose cellulose used to make the sponge, followed by treatment with heat or acid which causes coagulation and regeneration into a sponge. The sponge is rinsed, leaving a porous structure having the chelating polymer in it. This is followed by the addition of a potentiator (i.e., an antimicrobial agent) which is believed to react with the metal ion.
However, a need exists for methods of making durable long-lasting anti-microbial articles which do not require regeneration or further processing of the final article.